how do I keep my workstations from upgrading to IE 10?

how do I keep my workstations from upgrading to IE10? It seems like everyday I getting a complaint about the "The NETWORK is not allowing me to go to certain websites". Of course I knew that wasn't the case, BUT all of a sudden users cant browse websites they have been browsing since IE8. After a little digging I find they have been upgraded to IE10 behind my back (thank you windows automatic update) & now have 125 users who cannot reach web-applications needed for work. The admins went to work right away downgrading to IE9. We got 110 completed to come in the very next day to almost all of them back to IE10. We forgot to hide the update after the downgrade. :(